Countess by Coincidence is Book 3 in the House of Haverstock series (three connected marriage-of-convenience love stories set in Regency England).
Lady by Chance (Book 1 in the series) introduced the Haverstock family and spent two years on bestselling lists for historical romances.
In Duchess by Mistake (Book 2) an innocent visit to the Duke of Aldridge's to request a donation for her war widows puts Lady Elizabeth Upton in the midst of a most shocking scandal. . .